Process for incorporating graphene into a core of a golf ball

ABSTRACT

A method for forming a golf ball with a graphene core disclosed herein. The method includes mixing a graphene masterbatch material with a polybutadiene material to form a core mixture, wherein the graphene masterbatch material comprises graphene in an amount from 0.1 to 80.0 weight percent of the graphene masterbatch material mixed with a carrier polymer in an amount from 99.9 to 20 weight percent of the graphene masterbatch material.

CROSS REFERENCES TO RELATED APPLICATIONS

The Present Application U.S. patent application Ser. No. 15/705,011,filed on Sep. 14, 2017, which is a continuation-in-part application ofU.S. patent application Ser. No. 15/436,169, filed on Feb. 17, 2017,which claims priority to U.S. Provisional Patent Application No.62/401,034, filed on Sep. 28, 2016, each of which is hereby incorporatedby reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to the use of graphene andcarbon nanotubes in layers of a golf ball.

Description of the Related Art

Graphene is a two dimensional form of carbon that has some very unusualmechanical, thermal, and electrical properties. For example, it is morethan 100 times stronger than steel, thermally more conductive thansilver, and electrically more conductive than copper. Benefits ofgraphene can be utilized in composites to obtain materials withexcellent mechanical, thermal, and electrical properties. To achievethis improvement, however, uniform dispersion of graphene in compositematrix such as polymer is extremely important. Graphene in powdered formtends to form aggregates and may in fact hurt final properties ofcomposites if not dispersed properly. Various examples can be found inliterature that emphasize the need for uniform dispersion. For example,Tang et al. demonstrated higher mechanical strength and electricalconductivity for epoxy composites with well dispersed graphene comparedto composites that had poorly dispersed graphene. Teng et al. usedfunctional polymers to disperse graphene that resulted in more than 20%improvement in thermal conductivity of epoxy composite compared topoorly dispersed graphene. Wan et al. describe use of surfactant toimprove graphene dispersion in an epoxy based nanocomposite which showsbetter tensile strength compared to non-surfactant based graphene-epoxynanocomposite. Xu et al. used simple vacuum filtration technique toachieve uniform dispersion of graphene in polyvinyl alcohol basedcomposites. They attribute increased mechanical strength to the uniformdispersion of graphene that improves graphene polymer interaction. Songet al. talk about improving graphene dispersion by coating it withpolypropylene based latex. Coated graphene is then incorporated in apolypropylene matrix to obtain polypropylene composite with highertensile strength and Young's modulus. Naebe et al. describe a chemicalfunctionalization method of graphene that improves its dispersion in anepoxy matrix to such an extent that with just 0.1% wt functionalizedgraphene results in more than 20% increase in flexural strength. U.S.Pat. No. 8,287,699 B2 describes chemically functionalizing graphene withgroups such as bromide and then using this functional group to carry outin-situ polymerization of styrene to obtain a polystyrene/graphenenanocomposite. U.S. Pat. No. 8,652,362 B2 talks about functionalizinggraphene with epoxy groups for better incorporation in an epoxy polymermatrix. A composite material made from this graphene based epoxy andcuring agent showed better electrical conductivity than composite thatcontained un-modified graphene. U.S. Pat. No. 7,745,528 B2 describeusing functionalized graphene in solvent such as tetrahydrofuran forbetter dispersion in a polydimethylsiloxane based composite. U.S. Pat.No. 7,914,844 B2 describe using oxidized graphene solution to dissolve apolymer. This polymer graphene solution is then chemically reduced anddried to obtain a composite with better electrical conductivity. Theyattribute increased electrical conductivity to the reduced nature ofgraphene that has lesser oxygen content than oxidized graphene.

Most of the methods mentioned in the literature use chemicalfunctionalization methods, ultrasonication or solvents for dispersinggraphene in a polymer matrix. There is need to design a better processwhere a good dispersion of graphene is achieved without the need to useany oxidizing/reducing agents or solvents.

BRIEF SUMMARY OF THE INVENTION

The primary purpose of the present invention is to enhance thedurability of golf ball rubber core by using nanofillers such asgraphene in a well dispersed form. Good dispersion of graphene in coreis achieved by using it in a masterbatch form and not in a powder form.Carrier polymers used in masterbatch, include but are not limited to,polybutadiene, polyisoprene, polyisobutylene, EPDM, polyethyleneionomer, maleic anhydride functionalized polyethylene, styrene butadienerubber, styrene isoprene rubber, and butyl rubber.

Another objective is to improve aging properties due to theincorporation of graphene in the core for better retention ofcompression and COR over time.

The graphene gets mixed twice, once during masterbatch process andsecond when it is added to a rubber core mixture.

Incorporation is dust free, graphene stays in masterbatch.

Various golf ball properties such as compression and COR can be changedby changing the carrier polymer present in the masterbatch.

One aspect of the present invention is a method for forming a core for agolf ball. The method includes mixing a graphene masterbatch materialwith a polybutadiene material to form a core mixture, wherein thegraphene masterbatch material comprises graphene in an amount from 0.1to 80.0 weight percent of the graphene masterbatch material mixed with acarrier polymer in an amount from 99.9 to 20 weight percent of thegraphene masterbatch material. The method also includes compressionmolding a core from the core mixture.

A more preferred embodiment of the method includes forming a cover overthe core.

A more preferred embodiment of the method includes forming a mantlelayer over the core.

A more preferred embodiment of the method includes that the core mixtureis molded over an inner core to produce a dual core with a diameterranging from 0.7 inch to 1.6 inches.

A more preferred embodiment of the method includes compression molding acore from the core mixture comprises compression molding an outer corelayer over a center core comprising a polybutadiene mixture.

A more preferred embodiment of the method includes compression molding acore from the core mixture comprises compression molding a center coreand an outer core over the center core, and the center core and theouter core comprise the core mixture.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an exploded partial cut-away view of a golf ball.

FIG. 2 is top perspective view of a golf ball.

FIG. 3 is a cross-sectional view of a core component of a golf ball.

FIG. 4 is a cross-sectional view of a core component and a mantlecomponent of a golf ball.

FIG. 5 is a cross-sectional view of an inner core layer, an outer corelayer, an inner mantle layer, an outer mantle layer and a cover layer ofa golf ball.

FIG. 5A is a cross-sectional view of an inner core layer, anintermediate core layer, an outer core layer, a mantle layer and a coverlayer of a golf ball.

FIG. 6 is a cross-sectional view of an inner core layer under a 100kilogram load.

FIG. 7 is a cross-sectional view of a core under a 100 kilogram load.

FIG. 8 is a cross-sectional view of a core component and a mantlecomponent of a golf ball.

FIG. 9 is a cross-sectional view of a core component, the mantlecomponent and a cover layer of a golf ball.

FIG. 10 is an exploded partial cut-away view of a four-piece golf ball.

FIG. 11 is an exploded partial cut-away view of a three-piece golf ball.

FIG. 12 is an exploded partial cut-away view of a two-piece golf ball.

FIG. 13 is a cross-sectional view of a two-piece golf ball.

FIG. 14 is a cross-sectional view of a three-piece golf ball.

FIG. 15 is an exploded partial cut-away view of a three-piece golf ball.

FIG. 16 is a cross-sectional view of a three-piece golf ball with a dualcore and a cover.

FIG. 17 is a cross-sectional view of a three-piece golf ball with acore, mantle and cover.

FIG. 18 is a cross-sectional view of a four-piece golf ball with a dualcore, mantle layer and a cover.

FIG. 19 is a cross-sectional view of a four-piece golf ball with a core,dual mantle layers and a cover.

FIG. 20 is a graph of durability testing of outer cores using PTM at 175fps.

DETAILED DESCRIPTION OF THE INVENTION

In a typical rubber mixer such as Banburry or Kneader, 7.5 lbs ofgraphene was blended with 30 lbs of polybutadiene rubber. Mixing wasdone at temperatures between room temperature to 400 F for times between1 min to 40 min. More mixing was later done on a two roll mill. Mixingtemperature mentioned in the processes above can have a wide range suchas −130 F to the thermal degradation temperature of carrier polymer.Although mixing time is mentioned in minutes, it can be done for anytimefrom few seconds to minutes or few hours. Although economically notviable, mixing can also be done for few days.

The Masterbatch is made of 1-80% by weight of graphene or and carbonnanotube and 20-99% by weight of a polymer.

Carrier polymers used in masterbatch include, but are not limited to,polybutadiene, polyisoprene, polyisobutylene, EPDM, polyethyleneionomer, maleic anhydride functionalized polyethylene, styrene butadienerubber, styrene isoprene rubber, and butyl rubber.

Masterbatch can be made by mixing polymer and graphene or and carbonnanotube in an internal mixer and then optionally additional mixing canbe done on a two roll mill.

The masterbatch can be added to a typical golf core recipe at 1-60% byweight.

The dispersion of nanofillers such as graphene or and carbon nanotubesin a rubber core can be improved by using masterbatch of these fillers.Nanofillers by themselves have a tendency to form aggregates. Usingmasterbatch helps disperse polymer between layers/tubes of nanofillerswhich facilitates their further incorporation in a rubber core.

Better dispersion is obtained since these nanofillers get mixed twice(once during masterbatch process and second during golf ball core mixingprocess).

This process prevents dust formation since nanofiller is added in amasterbatch form and not in a powder.

This process is environmentally friendly since it does not use anystrong solvent, any strong oxidizing or reducing agents for modifying ordispersing graphene

No post or pre-treatment of graphene is needed for its dispersion in apolymer matrix

No ultra-sonication of graphene is required.

Polybutadiene based cores were made using following materials.Corresponding levels (by % wt) is mentioned next to each material:Polybutadiene with more than 60% 1,4-cis structure-(40-90%);Polyisoprene-(1-30%); Zinc diacrylate-(10-50%); Zinc oxide-(1-30%); Zincstearate-(1-20%); Peroxide initiator-(0.1-10%); Zincpentachlorothiophenol-(0-10%); Color-(0-10%); Barium sulfate-(0-20%);Graphene-(0.01-6%)-available from various suppliers such as Cheap TubesInc., Ad-Nano Technologies Private Limited, MKnano, XG Sciences Inc.,Angstron Materials Inc. which has a surface area between 150-1000 m²/g;Graphene masterbatch (a masterbatch with 5-95% polybutadiene orpolyisoprene and 1-10% graphene)-(0.1-50%)-custom compounding can bedone with the help of various suppliers such as Preferred CompoundingCorp, Dyna-Mix, Alttran, Callaway (in house compounding;CNT-(0.01-6%)-available from various suppliers such as Bayer MaterialScience, Future Carbon, Cheap Tubes Inc, NanoAmor, Nanocyl, Nanocyl SA,Arkema, NanoTechLabs, Inc.; CNT masterbatch (a masterbatch of with 5-95%polyisoprene and 1-95% CNT)-(01-50%)-masterbatches or custommasterbatches are available from various suppliers such as Cheap TubesInc, Nanocyl SA, Arkema, NanoTechLabs, Inc.

Dual Cores with Graphene/CNT in the Outer Core.

In this study graphene, CNT, and a mixture of graphene and CNT wereintroduced to the outer core in a dual core construction. Dual coreswere made by compression molding two outer core halves around an alreadymolded inner core having a diameter of approximately 0.940″ and a softcompression of approximately 0.210 inches of deflection under a 200 lbload. Curing of the inner and outer core was done at temperaturesranging between 150-400 F for times ranging from 1-30 minutes. Aftermolding, the dual cores were spherically ground to approximately 1.560″prior to testing.

Table 1 and 2 give details of recipe of inner and outer cores.Components from these recipes were mixed in an internal mixer.Optionally, additional mixing was done using a two roll mill.

Compression of the outer core is measured by first making a full sizecore separately, measuring its compression, and then molding two halvesaround the inner core to complete the dual core. Compressiondifferential describes the difference between the outer core compression(as molded independently) and inner core compression. A highercompression differential is more susceptible to crack durability uponimpact.

TABLE 1 Inner core recipe % wt Components Polybutadiene rubber 70.1Polyisoprene rubber 0.0 Zinc diacrylate 15.9 Zinc oxide 7.0 Zincstearate 0.0 Peroxide initiator 1.1 Zinc pentachlorothiophenol 0.6 Color0.1 Barium sulfate 0.0 graphene 0.0 graphene masterbatch 0.0 CNT 0.0 CNTMasterbatch 0.0 Properties Compression 0.210

TABLE 3 Outer core recipe of dual core Formula 4 (0.8% Formula 1 Formula2 Formula 3 Graphene + (0% (0.8% (0.8% CNT Graphene) Graphene) CNT)mixture) % wt % wt % wt % wt Components Polybutadiene 63.3 62.5 62.562.5 Zinc Diacrylate 26.3 26.9 26.9 26.9 Zinc Oxide 6.3 5.9 5.9 5.9 ZincStearate 0.0 0.0 0.0 0.0 Peroxide initiator 0.5 0.5 0.5 0.5 Zinc 0.6 0.60.6 0.6 pentachlorothiophenol Color 0.1 0.1 0.1 0.1 Limestone 0.0 0.00.0 0.0 Tungsten 0.0 0.0 0.0 0.0 Barium sulfate 2.9 2.8 2.8 2.8 Graphene0.0 0.0 0.0 0.0 Graphene in 0.0 0.8 0.0 0.4 masterbatch CNT 0.0 0.0 0.00.0 CNT added in 0.0 0.0 0.8 0.4 masterbatch form Properties of outercore Compression 100.7 101.2 102.3 102.2 COR (coefficient of 0.816 0.8090.806 0.808 restitution) Properties of dual core built from inner andouter core Compression 81.3 82.7 86.3 85.1 COR (coefficient of 0.8120.808 0.808 0.809 restitution @ 125 fps) Durability score or 21 62 73 65mean time to fail MTTF (number of shots after which ball starts tocrack/fail)

Compression is measured by applying a 200 pound load to the core andmeasuring its deflection, in inches. Compression=180−(deflection*1000)

Durability Testing of Dual Cores

Cores were shot at 175 fps in a pneumatic testing machine (PTM).

For each formula mentioned in Table 2, 12 cores were tested. Number ofshots after which each core cracked was recorded for each core, and thecracked core was removed from the remainder of the test. The data wasreported using a Weibull plot, and the mean time to fail was reported asshown in Table 2. As seen in FIG. 1, graphene/CNT modified cores enduredmore shots before failure compared to cores with no graphene/CNT. It isreasonable to assume that the durability of a golf ball having a dualcore of this design will also experience a dramatic increase in crackdurability based on this improvement to the dual core. It is reasonableto assume that the addition of graphene/CNT in the inner core couldprovide a durability enhancement to the overall golf ball, but thisstudy only focused on the outer core.

As our experiment has shown, incorporating graphene and CNT into theouter core recipe reinforces the strength of the outer core and providesgreater crack durability protection in the design of a dual core golfball, which is more susceptible to crack durability failures if theouter core is much firmer than the soft inner core.

FIGS. 1, 3, 4 and 5 illustrate a five piece golf ball 10 comprising aninner core 12 a, an outer core 12 b, an inner mantle 14 a, an outermantle 14 b, and a cover 16, wherein the cover layer 16 is composed of athermoplastic polyurethane and has a Shore A hardness less than 90. Theinner core 12 a comprises polybutadiene mixture comprising 0.4 to 2.5weight percent of a graphene.

FIG. 5A illustrates a five piece golf ball 10 comprising an inner core12 a, an intermediate core 12 b, an outer core 12 c, a mantle 14, and acover 16, wherein the cover layer 16 is composed of a thermoplasticpolyurethane. The intermediate core 12 b comprises polybutadiene mixturecomprising 0.4 to 2.5 weight percent of a graphene.

FIGS. 8 and 9 illustrate a six piece golf ball 10 comprising an innercore 12 a, an intermediate core 12 b, an outer core 12 c, an innermantle 14 a, an outer mantle 14 b, and a cover 16, wherein the coverlayer 16 is composed of a thermoplastic polyurethane. The inner core 12a comprises polybutadiene mixture comprising 0.4 to 2.5 weight percentof a graphene.

FIG. 10 illustrates a four piece golf ball comprising a dual core, aboundary layer and a cover. The outer core comprises polybutadienemixture comprising 0.4 to 2.5 weight percent of a graphene.

FIG. 11 illustrates a three piece golf ball comprising a core, aboundary layer and a cover. The core comprises polybutadiene mixturecomprising 0.4 to 2.5 weight percent of a graphene.

FIGS. 12 and 13 illustrate a two piece golf ball 20 with a core 25 and acover 30. The core comprises polybutadiene mixture comprising 0.4 to 2.5weight percent of a graphene.

FIGS. 14 and 15 illustrate a three-piece golf ball 5 comprising a core10, a mantle layer 14 and a cover 16 with dimples 18, wherein the corecomprises 0.4 to 2.5 weight percent of a graphene.

FIG. 16 illustrates a dual core three piece golf ball 35 comprising aninner core 30, and outer core 32 and a cover 34, wherein the corecomprises 0.4 to 2.5 weight percent of a graphene.

FIG. 17 illustrates a three piece golf ball 45 comprising a core 40, amantle layer 42 and a cover 44, wherein the core comprises 0.4 to 2.5weight percent of a graphene.

FIG. 18 illustrates a dual core four piece golf ball 55 comprising aninner core 50, an outer core 52, a mantle layer 54 and a cover 56,wherein the core comprises 0.4 to 2.5 weight percent of a graphene.

FIG. 19 illustrates a four piece golf ball 65 comprising a core 60, aninner mantle 62, an outer mantle 64 and a cover 66, wherein the corecomprises 0.4 to 2.5 weight percent of a graphene.

The mantle component is preferably composed of the inner mantle layerand the outer mantle layer. The mantle component preferably has athickness ranging from 0.05 inch to 0.15 inch, and more preferably from0.06 inch to 0.08 inch. The outer mantle layer is preferably composed ofa blend of ionomer materials. One preferred embodiment comprises SURLYN9150 material, SURLYN 8940 material, a SURLYN AD1022 material, and amasterbatch. The SURLYN 9150 material is preferably present in an amountranging from 20 to 45 weight percent of the cover, and more preferably30 to 40 weight percent. The SURLYN 8945 is preferably present in anamount ranging from 15 to 35 weight percent of the cover, morepreferably 20 to 30 weight percent, and most preferably 26 weightpercent. The SURLYN 9945 is preferably present in an amount ranging from30 to 50 weight percent of the cover, more preferably 35 to 45 weightpercent, and most preferably 41 weight percent. The SURLYN 8940 ispreferably present in an amount ranging from 5 to 15 weight percent ofthe cover, more preferably 7 to 12 weight percent, and most preferably10 weight percent.

SURLYN 8320, from DuPont, is a very-low modulus ethylene/methacrylicacid copolymer with partial neutralization of the acid groups withsodium ions. SURLYN 8945, also from DuPont, is a high acidethylene/methacrylic acid copolymer with partial neutralization of theacid groups with sodium ions. SURLYN 9945, also from DuPont, is a highacid ethylene/methacrylic acid copolymer with partial neutralization ofthe acid groups with zinc ions. SURLYN 8940, also from DuPont, is anethylene/methacrylic acid copolymer with partial neutralization of theacid groups with sodium ions.

The inner mantle layer is preferably composed of a blend of ionomers,preferably comprising a terpolymer and at least two high acid (greaterthan 18 weight percent) ionomers neutralized with sodium, zinc,magnesium, or other metal ions. The material for the inner mantle layerpreferably has a Shore D plaque hardness ranging preferably from 35 to77, more preferably from 36 to 44, a most preferably approximately 40.The thickness of the outer mantle layer preferably ranges from 0.025inch to 0.050 inch, and is more preferably approximately 0.037 inch. Themass of an insert including the dual core and the inner mantle layerpreferably ranges from 32 grams to 40 grams, more preferably from 34 to38 grams, and is most preferably approximately 36 grams. The innermantle layer is alternatively composed of a HPF material available fromDuPont. Alternatively, the inner mantle layer 14 b is composed of amaterial such as disclosed in Kennedy, III et al., U.S. Pat. No.7,361,101 for a Golf Ball And Thermoplastic Material, which is herebyincorporated by reference in its entirety.

The outer mantle layer is preferably composed of a blend of ionomers,preferably comprising at least two high acid (greater than 18 weightpercent) ionomers neutralized with sodium, zinc, or other metal ions.The blend of ionomers also preferably includes a masterbatch. Thematerial of the outer mantle layer preferably has a Shore D plaquehardness ranging preferably from 55 to 75, more preferably from 65 to71, and most preferably approximately 67. The thickness of the outermantle layer preferably ranges from 0.025 inch to 0.040 inch, and ismore preferably approximately 0.030 inch. The mass of the entire insertincluding the core, the inner mantle layer and the outer mantle layerpreferably ranges from 38 grams to 43 grams, more preferably from 39 to41 grams, and is most preferably approximately 41 grams.

In an alternative embodiment, the inner mantle layer is preferablycomposed of a blend of ionomers, preferably comprising at least two highacid (greater than 18 weight percent) ionomers neutralized with sodium,zinc, or other metal ions. The blend of ionomers also preferablyincludes a masterbatch. In this embodiment, the material of the innermantle layer has a Shore D plaque hardness ranging preferably from 55 to75, more preferably from 65 to 71, and most preferably approximately 67.The thickness of the outer mantle layer preferably ranges from 0.025inch to 0.040 inch, and is more preferably approximately 0.030 inch.Also in this embodiment, the outer mantle layer 14 b is composed of ablend of ionomers, preferably comprising a terpolymer and at least twohigh acid (greater than 18 weight percent) ionomers neutralized withsodium, zinc, magnesium, or other metal ions. In this embodiment, thematerial for the outer mantle layer 14 b preferably has a Shore D plaquehardness ranging preferably from 35 to 77, more preferably from 36 to44, a most preferably approximately 40. The thickness of the outermantle layer preferably ranges from 0.025 inch to 0.100 inch, and morepreferably ranges from 0.070 inch to 0.090 inch.

In yet another embodiment wherein the inner mantle layer is thicker thanthe outer mantle layer and the outer mantle layer is harder than theinner mantle layer, the inner mantle layer is composed of a blend ofionomers, preferably comprising a terpolymer and at least two high acid(greater than 18 weight percent) ionomers neutralized with sodium, zinc,magnesium, or other metal ions. In this embodiment, the material for theinner mantle layer has a Shore D plaque hardness ranging preferably from30 to 77, more preferably from 30 to 50, and most preferablyapproximately 40. In this embodiment, the material for the outer mantlelayer has a Shore D plaque hardness ranging preferably from 40 to 77,more preferably from 50 to 71, and most preferably approximately 67. Inthis embodiment, the thickness of the inner mantle layer preferablyranges from 0.030 inch to 0.090 inch, and the thickness of the outermantle layer ranges from 0.025 inch to 0.070 inch.

Preferably the inner core has a diameter ranging from 0.75 inch to 1.20inches, more preferably from 0.85 inch to 1.05 inch, and most preferablyapproximately 0.95 inch. Preferably the inner core 12 a has a Shore Dhardness ranging from 20 to 50, more preferably from 25 to 40, and mostpreferably approximately 35. Preferably the inner core has a massranging from 5 grams to 15 grams, 7 grams to 10 grams and mostpreferably approximately 8 grams.

Preferably the outer core has a diameter ranging from 1.25 inch to 1.55inches, more preferably from 1.40 inch to 1.5 inch, and most preferablyapproximately 1.5 inch. Preferably the outer core has a Shore D surfacehardness ranging from 40 to 65, more preferably from 50 to 60, and mostpreferably approximately 56. Preferably the outer core is formed from apolybutadiene, zinc diacrylate, zinc oxide, zinc stearate, a peptizerand peroxide. Preferably the combined inner core and outer core have amass ranging from 25 grams to 35 grams, 30 grams to 34 grams and mostpreferably approximately 32 grams.

Preferably the inner core has a deflection of at least 0.230 inch undera load of 220 pounds, and the core has a deflection of at least 0.080inch under a load of 200 pounds. As shown in FIGS. 6 and 7, a mass 50 isloaded onto an inner core and a core. As shown in FIGS. 6 and 7, themass is 100 kilograms, approximately 220 pounds. Under a load of 100kilograms, the inner core preferably has a deflection from 0.230 inch to0.300 inch. Under a load of 100 kilograms, preferably the core has adeflection of 0.08 inch to 0.150 inch. Alternatively, the load is 200pounds (approximately 90 kilograms), and the deflection of the core 12is at least 0.080 inch. Further, a compressive deformation from abeginning load of 10 kilograms to an ending load of 130 kilograms forthe inner core ranges from 4 millimeters to 7 millimeters and morepreferably from 5 millimeters to 6.5 millimeters. The dual coredeflection differential allows for low spin off the tee to providegreater distance, and high spin on approach shots.

In an alternative embodiment of the golf ball shown in FIG. 5A, the golfball 10 comprises an inner core 12 a, an intermediate core 12 b, anouter core 12 b, a mantle 14 and a cover 16. The golf ball 10 preferablyhas a diameter of at least 1.68 inches, a mass ranging from 45 grams to47 grams, a COR of at least 0.79, a deformation under a 100 kilogramloading of at least 0.07 mm.

In one embodiment, the golf ball comprises a core, a mantle layer and acover layer. The core comprises an inner core sphere, an intermediatecore layer and an outer core layer. The intermediate core layer iscomposed of a highly neutralized ionomer and has a Shore D hardness lessthan 40. The outer core layer is composed of a highly neutralizedionomer and has a Shore D hardness less than 45. A thickness of theintermediate core layer is greater than a thickness of the outer corelayer. The mantle layer is disposed over the core, comprises an ionomermaterial and has a Shore D hardness greater than 55. The cover layer isdisposed over the mantle layer comprises a thermoplastic polyurethanematerial and has a Shore A hardness less than 100. The golf ball has adiameter of at least 1.68 inches. The mantle layer is harder than theouter core layer, the outer core layer is harder than the intermediatecore layer, the intermediate core layer is harder than the inner coresphere, and the cover layer is softer than the mantle layer.

In another embodiment, shown in FIGS. 8 and 9, the golf ball 10 has amulti-layer core and multi-layer mantle. The golf ball includes a core,a mantle component and a cover layer. The core comprises an inner coresphere, an intermediate core layer and an outer core layer. The innercore sphere comprises a TPEE material and has a diameter ranging from0.875 inch to 1.4 inches. The intermediate core layer is composed of ahighly neutralized ionomer and has a Shore D hardness less than 40. Theouter core layer is composed of a highly neutralized ionomer and has aShore D hardness less than 45. A thickness of the intermediate corelayer is greater than a thickness of the outer core layer 12 c. Theinner mantle layer is disposed over the core, comprises an ionomermaterial and has a Shore D hardness greater than 55. The outer mantlelayer is disposed over the inner mantle layer, comprises an ionomermaterial and has a Shore D hardness greater than 60. The cover layer isdisposed over the mantle component, comprises a thermoplasticpolyurethane material and has a Shore A hardness less than 100. The golfball has a diameter of at least 1.68 inches. The outer mantle layer isharder than the inner mantle layer, the inner mantle layer is harderthan the outer core layer, the outer core layer is harder than theintermediate core layer, the intermediate core layer is harder than theinner core sphere, and the cover layer is softer than the outer mantlelayer.

In a particularly preferred embodiment of the invention, the golf ballpreferably has an aerodynamic pattern such as disclosed in Simonds etal., U.S. Pat. No. 7,419,443 for a Low Volume Cover For A Golf Ball,which is hereby incorporated by reference in its entirety.Alternatively, the golf ball has an aerodynamic pattern such asdisclosed in Simonds et al., U.S. Pat. No. 7,338,392 for An AerodynamicSurface Geometry For A Golf Ball, which is hereby incorporated byreference in its entirety.

Various aspects of the present invention golf balls have been describedin terms of certain tests or measuring procedures. These are describedin greater detail as follows.

As used herein, “Shore D hardness” of the golf ball layers is measuredgenerally in accordance with ASTM D-2240 type D, except the measurementsmay be made on the curved surface of a component of the golf ball,rather than on a plaque. If measured on the ball, the measurement willindicate that the measurement was made on the ball. In referring to ahardness of a material of a layer of the golf ball, the measurement willbe made on a plaque in accordance with ASTM D-2240. Furthermore, theShore D hardness of the cover is measured while the cover remains overthe mantles and cores. When a hardness measurement is made on the golfball, the Shore D hardness is preferably measured at a land area of thecover.

As used herein, “Shore A hardness” of a cover is measured generally inaccordance with ASTM D-2240 type A, except the measurements may be madeon the curved surface of a component of the golf ball, rather than on aplaque. If measured on the ball, the measurement will indicate that themeasurement was made on the ball. In referring to a hardness of amaterial of a layer of the golf ball, the measurement will be made on aplaque in accordance with ASTM D-2240. Furthermore, the Shore A hardnessof the cover is measured while the cover remains over the mantles andcores. When a hardness measurement is made on the golf ball, Shore Ahardness is preferably measured at a land area of the cover

The resilience or coefficient of restitution (COR) of a golf ball is theconstant “e,” which is the ratio of the relative velocity of an elasticsphere after direct impact to that before impact. As a result, the COR(“e”) can vary from 0 to 1, with 1 being equivalent to a perfectly orcompletely elastic collision and 0 being equivalent to a perfectly orcompletely inelastic collision.

COR, along with additional factors such as club head speed, club headmass, ball weight, ball size and density, spin rate, angle of trajectoryand surface configuration as well as environmental conditions (e.g.temperature, moisture, atmospheric pressure, wind, etc.) generallydetermine the distance a ball will travel when hit. Along this line, thedistance a golf ball will travel under controlled environmentalconditions is a function of the speed and mass of the club and size,density and resilience (COR) of the ball and other factors. The initialvelocity of the club, the mass of the club and the angle of the ball'sdeparture are essentially provided by the golfer upon striking. Sinceclub head speed, club head mass, the angle of trajectory andenvironmental conditions are not determinants controllable by golf ballproducers and the ball size and weight are set by the U.S.G.A., theseare not factors of concern among golf ball manufacturers. The factors ordeterminants of interest with respect to improved distance are generallythe COR and the surface configuration of the ball.

The coefficient of restitution is the ratio of the outgoing velocity tothe incoming velocity. In the examples of this application, thecoefficient of restitution of a golf ball was measured by propelling aball horizontally at a speed of 125+/−5 feet per second (fps) andcorrected to 125 fps against a generally vertical, hard, flat steelplate and measuring the ball's incoming and outgoing velocityelectronically. Speeds were measured with a pair of ballistic screens,which provide a timing pulse when an object passes through them. Thescreens were separated by 36 inches and are located 25.25 inches and61.25 inches from the rebound wall. The ball speed was measured bytiming the pulses from screen 1 to screen 2 on the way into the reboundwall (as the average speed of the ball over 36 inches), and then theexit speed was timed from screen 2 to screen 1 over the same distance.The rebound wall was tilted 2 degrees from a vertical plane to allow theball to rebound slightly downward in order to miss the edge of thecannon that fired it. The rebound wall is solid steel.

As indicated above, the incoming speed should be 125±5 fps but correctedto 125 fps. The correlation between COR and forward or incoming speedhas been studied and a correction has been made over the ±5 fps range sothat the COR is reported as if the ball had an incoming speed of exactly125.0 fps.

The measurements for deflection, compression, hardness, and the like arepreferably performed on a finished golf ball as opposed to performingthe measurement on each layer during manufacturing.

Preferably, in a five layer golf ball comprising an inner core, an outercore, an inner mantle layer, an outer mantle layer and a cover, thehardness/compression of layers involve an inner core with the greatestdeflection (lowest hardness), an outer core (combined with the innercore) with a deflection less than the inner core, an inner mantle layerwith a hardness less than the hardness of the combined outer core andinner core, an outer mantle layer with the hardness layer of the golfball, and a cover with a hardness less than the hardness of the outermantle layer. These measurements are preferably made on a finished golfball that has been torn down for the measurements.

Preferably the inner mantle layer is thicker than the outer mantle layeror the cover layer. The dual core and dual mantle golf ball creates anoptimized velocity-initial velocity ratio (Vi/IV), and allows for spinmanipulation. The dual core provides for increased core compressiondifferential resulting in a high spin for short game shots and a lowspin for driver shots. A discussion of the USGA initial velocity test isdisclosed in Yagley et al., U.S. Pat. No. 6,595,872 for a Golf Ball WithHigh Coefficient Of Restitution, which is hereby incorporated byreference in its entirety. Another example is Bartels et al., U.S. Pat.No. 6,648,775 for a Golf Ball With High Coefficient Of Restitution,which is hereby incorporated by reference in its entirety.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

We claim as our invention the following:
 1. A method for forming a golfball with a graphene core, the method comprising: mixing a graphenemasterbatch material with a polybutadiene material to form a coremixture, the core mixture comprising a polybutadiene in an amountranging from 40 to 90 weight percent, zinc diacrylate in an amountranging from 10 to 50 weight percent, zinc oxide in an amount rangingfrom 1 to 30 weight percent, peroxide initiator in an amount rangingfrom 0.1 to 10 weight percent, and 0.4 to 2.5 weight percent graphenematerial, wherein the graphene masterbatch material comprises graphenein an amount from 0.1 to 80.0 weight percent of the graphene masterbatchmaterial mixed with a carrier polymer in an amount from 99.9 to 20weight percent of the graphene masterbatch material, wherein thegraphene material has a surface area ranging from 150 m²/g to 1000 m²/g;and compression molding a core from the core mixture.
 2. The methodaccording to claim 1 wherein the core has a diameter ranging from 0.70inch to 1.6 inch.
 3. The method according to claim 1 further comprisingforming a cover over the core.
 4. The method according to claim 1further comprising forming a mantle layer over the core.
 5. The methodaccording to claim 4 wherein the carrier polymer material is selectedfrom the group consisting of polybutadiene, polyisoprene,polyisobutylene, EPDM, polyethylene ionomer, maleic anhydridefunctionalized polyethylene, styrene butadiene rubber, styrene isoprenerubber, and butyl rubber.
 6. The method according to claim 1 whereincompression molding a core from the core mixture comprises compressionmolding a center core.
 7. The method according to claim 1 whereincompression molding a core from the core mixture comprises compressionmolding an outer core layer over a center core comprising apolybutadiene mixture.
 8. The method according to claim 1 whereincompression molding a core from the core mixture comprises compressionmolding a center core and an outer core over the center core, and thecenter core and the outer core comprise the core mixture.
 9. A methodfor forming a golf ball with a graphene core, the method comprising:mixing a graphene masterbatch material with a polybutadiene material toform a core mixture, the core mixture comprising a polybutadiene in anamount ranging from 40 to 90 weight percent, zinc diacrylate in anamount ranging from 10 to 50 weight percent, zinc oxide in an amountranging from 1 to 30 weight percent, peroxide initiator in an amountranging from 0.1 to 10 weight percent, and 0.4 to 2.5 weight percentgraphene material, wherein the graphene masterbatch material comprisesgraphene in an amount from 0.1 to 1.0 weight percent of the graphenemasterbatch material mixed with a carrier polymer in an amount from 99.9to 99 weight percent of the graphene masterbatch material, wherein thegraphene material has a surface area ranging from 150 m²/g to 1000 m²/g;and compression molding a core from the core mixture.